William E. Lynch Jr. Co-Owner, Manager Millcreek Perch Farm Marysville, OH

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1 William E. Lynch Jr. Co-Owner, Manager Millcreek Perch Farm Marysville, OH Chair, Industry Advisory Council North Central Regional Aquaculture Center

2 Aquaculture Realism A Severely or Chronically Stressed Fish is a Dead Fish Severe stress is typically caused by a sudden event, causing death within minutes or up to a day. Chronic stress is longer term exposure to poor living conditions, causing impairment to the immune system. A chronically stressed fish is a diseased fish and then eventually a dead fish

3 An Interesting Insight A close aquaculture friend recently told me A Successful Fish Culturist is not successful because he or she is a successful biologist, physiologist etc ; No, he or she is successful in large part because he or she is a successful water quality and aquatic waste management specialist. If you successfully degrade generated fish wastes and uneaten food safely and therefore maintain excellent water quality, the fish will take care of themselves.

4 Water Quality BMP I Set Realistic Production Goals! In aerated Midwest ponds, a realistic production goal is 3000 pounds of fish per acre. Above that requires increasing the pond s ability to digest additional wastes. In RAS systems, production is based on gallons of water (living space) and the size of the filtration systems. ½ lb. per gallon of water. In flow-through systems, production is essentially based on gallons of water and exchange rate. Flushing of wastes.

5 Water Quality BMP II Monitor the Right Parameters & Know Why! Water temperature Dissolved oxygen ph Nitrogen compounds Nitrite Ammonia Un-ionized ammonia Alkalinity Carbon dioxide SRAC has fantastic factsheets on water quality!

6 Water Temperature Each fish species has upper lethal thermal limits. Ex. Rainbow trout will start dying once water temps exceed 68 F. Elevated water temps can cause stress, leading to health issues. High water temps also negatively impact biological degradation of wastes. Bacteria less efficient! Needed to calculate un-ionized ammonia levels!

7 Dissolved Oxygen Less than 4 ppm can lead to chronic fish stress, less than 3 ppm can lead to fish deaths. Dissolved oxygen utilized by fish, plants, and bacteria. Bacteria most efficient in degrading wastes need oxygen! Aerobic bacteria. Strong pattern of daily and seasonal variation.

8 ph Most fish species tolerate well, chronic exposure to lower & higher can become problematic. Avoid sudden changes! Bacteria critical to waste degradation function best at levels between 7.0 and 8.5. Needed to calculate un-ionized ammonia levels! Can be done with a meter! Easy! Higher ph in glaciated Ohio, common in Eastern Ohio. Strong daily variation due to carbon dioxide levels, which is related to plant & algae density.

9 Nitrogen Compounds

10 Nitrogen Compounds Nitrate (NO 3 ) Non-toxic up 200 ppm. Aquatic plants / algae quickly uptake nitrates. Nitrite (NO 2 ) Very toxic to fish at very low levels, causes brown blood disease. Fortunately, quickly converted to nitrates by bacteria. Rare in ponds, a real concern in tank culture. Total Ammonia (TAN) Ionized ammonia (NH 4+ ) Not toxic at typical pond levels, be careful in RAS! Un-ionized ammonia (NH 3 ) Reduced feeding at 0.06 ppm, mortality above 0.6 ppm. Levels increase with higher ph and water temperatures.

11 Water Quality BMP III Regularly monitor water quality parameters! Oxygen / Temperature (AM) Daily in ponds during warm weather and periods of heavy feeding. Once every 2-3 days otherwise. Twice a day (12 hrs. apart) in RAS systems. ph, nitrites, ammonia Once every 2-3 days in ponds during warm weather and periods of heavy feeding. Weekly otherwise. Twice a day in RAS systems. Carbon Dioxide, Alkalinity Weekly in ponds. Daily in RAS systems. Conditions can degrade very quickly in RAS systems, requires daily monitoring & attention.

12 Water Quality BMP IV Religiously record water quality data and set parameter goals! Allows one to monitor trends, can be proactive in preventing a potential problem. Provides a written historical record to look back over when similar concerns arise. A fish health specialist / veterinarian will always ask to look at recent water quality data when problems arise.

13 Water Quality Goals (0.5 m) Typical Published AM Oxygen > 4 ppm ph Hardness > 20 ppm Alkalinity > 90 ppm Nitrites < 0.05 ppm Carbon dioxide < 20 ppm Ammonia < 1 ppm Un-ionized ammonia < 0.06 ppm Millcreek Perch Farm s AM Oxygen > 5 ppm ph Hardness > 80 ppm Alkalinity > 150 ppm Nitrites < 0.02 ppm Carbon dioxide < 5 ppm Ammonia < 0.5 ppm Un-ionized ammonia = 0.02 ppm

14 Water Quality BMP V Monitor Water Quality Trends Trend monitoring allows assessment of how the production unit is functioning, whether it is a pond or a recirculating aquaculture system (RAS). Allows assessing impacts of changes to the unit, such as increased feeding. Can alert culturist to impending problems, thereby allowing a corrective action(s) to be instituted early. Water quality must be monitored regularly to allow development and evaluation of trends.

15 Oxygen: Daily Variation ( do monthly in ponds / weekly in RAS) 12 Hourly Oxygen Conc. (mg/l) Good Bad Disaster Hour

16 Oxygen: Growing Season Variation 12 6 AM Oxygen Conc. (mg/l) Good Bad 0 May June July Aug. Sept.

17 ph: Daily Variation (do monthly in ponds / weekly in RAS) 10 ph Bad Good Hour

18 Water Quality BMP VI Understand Factors that Influence Water Quality Parameters Sunlight / Photosynthesis Seasonal Water temperature Amount of aquatic plants / algae / planktonic algae Bacteria Interactions between monitored water quality parameters as well as above factors.

19 Factors Affecting Daily & Seasonal Oxygen Levels Sunlight Sunlight produces oxygen, BOD uses oxygen at night. Cloudy days lower daylight oxygen production, affecting night levels. After June 21, losing daylight. Water temperature Warm water holds less oxygen than cool water. Amount of aquatic plants / algae / planktonic algae Choked greenery elevates daytime oxygen to very high levels but night levels are very low (Respiration). Sudden die-off of planktonic algae major cause for concern. Aquatic plants / filamentous algae do not die-off suddenly unless you do it!

20 More Factors Affecting Daily & Seasonal Oxygen Levels Feeding Lower oxygen levels during periods of heavy feeding. Begin to elevate a pond s BOD quickly once feeding exceeds 15 lbsper day per acre. There is a feed / waste cumulative effect. Fish size 2 nd year growoutequals higher feed amounts in June, July, & August as compared to 1 st year fingerlings. Aeration Nighttime oxygen levels can be raised with vigorous surface aeration. Volume of oxygen-less water Increased volume of hypolimnion lacking oxygen lowers night levels.

21 Water Quality BMP VII Aerate your bacterial community! Pure oxygen in high-density RAS; bottom diffusers, or direction surface aeration in ponds. Prevents water column oxygen stratification in ponds. Better oxygen profile, including oxygen along the pond bottom. Improves aerobic bacteria abundance & efficiency. Enhances conversion of ammonia into harmless nitrates. Keeps un-ionized ammonia levels at very low levels if not zero.

22 Water Quality BMP VIII Encourage / Tolerate a Diverse Aquatic Plant Community! Combination of algae & submerged plants. Mitigates seasonal and daily boom & bust oxygen levels prevalent in ponds dominated by planktonic algae. Improves aerobic bacteria abundance & efficiency due to increased surface area on plant stems & leaves Enhances conversion of ammonia into harmless nitrates. Keeps un-ionized ammonia levels at very low levels if not zero.

23 Education! Education! Be a life-long learner! Use all sources of information on water quality, fish health, and fish husbandry. State extension programs Factsheets, bulletins, published articles, websites (SRAC) Workshops Other culturists! Create, review and re-work your own Water Quality & Fish Husbandry BMP it is a living document. Questions?